The present invention relates to metal forming dies and the like, in particular to a guided keeper assembly and associated method.
Metal forming dies, such as stamping dies and the like, are well known in the art. Progressive metal forming dies are unique, very sophisticated mechanisms which have multiple stations or progressions that are aligned longitudinally, and are designed to perform a specified operation at each station in a predetermined sequence to create a finished metal part. Progressive stamping dies are capable of forming complex metal parts at very high speeds, so as to minimize manufacturing costs.
Heretofore, the dies used in metal forming presses have typically been individually designed, one-of-a-kind assemblies for a particular part, with each of the various components being handcrafted and custom mounted or fitted in an associated die set, which is in turn positioned in a stamping press. Not only are the punches and the other forming tools in the die set individually designed and constructed, but the other parts of the die set, such as stock lifters, guides, end caps and keepers, cam returns, etc., are also custom designed, and installed in the die set. Current die making processes require carefully machined, precision holes and recesses in the die set for mounting the individual components, such that the same are quite labor intensive, and require substantial lead time to make, test and set up in a stamping press. Consequently, such metal forming dies are very expensive to design, manufacture and repair or modify.
FIGS. 4 and 5 illustrate a prior art metal forming die that includes a die shoe 1 and a die pad 2, which are interconnected for mutual reciprocation by a plurality of spools 3. A spring mechanism 4 is mounted between die shoe 1 and die pad 2, and resiliently urges die pad 2 to a fully extended position. A metal forming die 5 is mounted on the outer surface of die pad 2. Each of the spools 3 includes an enlarged head 6 which reciprocates in an associated counter bore 7 in the bottom of die shoe 1. The heads 6 of spools 3 engage the top of the associated counter bores 7 to positively retain die pad 2 in its fully extended position. The other ends 8 of spools 3 are attached to the corners of die pad 2. While such constructions have been generally successful, they do not precisely control reciprocation between die pad 2 and die shoe 1, particularly in high speed, progressive die applications.
FIGS. 6 and 7 illustrate another prior art configuration, wherein pressed in pins 10, with locator bushings 11, have been added to the spools 3 shown in FIG. 1 to more precisely control the reciprocation between die pad 2 and die shoe 1.
FIGS. 8 and 9 illustrate yet another prior art configuration, which includes guide pins 10 and bushings 11, but substitutes footed keepers 13 and 14 for the common spools 3 to positively limit the reciprocation between die pad 2 and die shoe 1. More specifically, footed keepers 13 are mounted to die pad 2, and engage mating footed keepers 14 which are mounted on die shoe 1.
While such prior art constructions are generally effective, they are complicated and expensive. A modular guided keeper which both precisely aligns the die shoe and die pad, and positively limits reciprocal travel therebetween would be clearly advantageous in simplifying metal forming die constructions and reducing the cost in designing, manufacturing, and repairing the same.